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.TH SIGWAITINFO 3C "Feb 5, 2008"
.SH NAME
sigwaitinfo, sigtimedwait \- wait for queued signals
.SH SYNOPSIS
.LP
.nf
#include <signal.h>

\fBint\fR \fBsigwaitinfo\fR(\fBconst sigset_t *restrict\fR \fIset\fR,
     \fBsiginfo_t *restrict\fR \fIinfo\fR);
.fi

.LP
.nf
\fBint\fR \fBsigtimedwait\fR(\fBconst sigset_t *restrict\fR \fIset\fR,
     \fBsiginfo_t *restrict\fR \fIinfo\fR,
     \fBconst struct timespec *restrict\fR \fItimeout\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The  \fBsigwaitinfo()\fR function selects the pending signal from the set
specified by \fBset\fR. Should any of multiple pending signals in the range
\fBSIGRTMIN\fR to \fBSIGRTMAX\fR be selected, it will be the lowest numbered
one. The selection order between realtime and non-realtime signals, or between
multiple pending non-realtime signals, is unspecified. If no signal in
\fBset\fR is pending at the time of the call, the calling thread is suspended
until one or more signals in \fBset\fR become pending or until it is
interrupted by an unblocked, caught signal.
.sp
.LP
The  \fBsigwaitinfo()\fR function behaves the same as the \fBsigwait\fR(2)
function if the \fIinfo\fR argument is \fINULL\fR. If the \fIinfo\fR argument
is non-\fINULL\fR, the \fBsigwaitinfo()\fR function behaves the same as
\fBsigwait\fR(2), except that the selected signal number is stored in the
\fIsi_signo\fR member, and the cause of the signal is stored in the
\fIsi_code\fR member. If any value is queued to the selected signal, the first
such queued value is dequeued and, if the \fIinfo\fR argument is
non-\fINULL\fR, the value is stored in the \fIsi_value\fR member of \fIinfo\fR.
The system resource used to queue the signal will be released and made
available to queue other signals. If no value is queued, the content of the
\fIsi_value\fR member is undefined. If no further signals are queued for the
selected signal, the pending indication for that signal will be reset. If the
value of the \fBsi_code\fR member is \fBSI_NOINFO\fR, only the \fBsi_signo\fR
member of \fBsiginfo_t\fR is meaningful, and the value of all other members is
unspecified.
.sp
.LP
The  \fBsigtimedwait()\fR function behaves the same as \fBsigwaitinfo()\fR
except that if none of the signals specified by \fBset\fR are pending,
\fBsigtimedwait()\fR waits for the time interval specified in the
\fBtimespec\fR structure referenced by \fItimeout\fR. If the \fBtimespec\fR
structure pointed to by \fItimeout\fR is zero-valued and if none of the signals
specified by \fBset\fR are pending, then \fBsigtimedwait()\fR returns
immediately with an error. If \fItimeout\fR is the \fINULL\fR pointer, the
behavior is unspecified.
.sp
.LP
If, while \fBsigwaitinfo()\fR or \fBsigtimedwait()\fR is waiting, a signal
occurs which is eligible for delivery (that is, not blocked by the process
signal mask), that signal is handled asynchronously and the wait is
interrupted.
.SH RETURN VALUES
.sp
.LP
Upon successful completion (that is, one of the signals specified by \fIset\fR
is pending or is generated) \fBsigwaitinfo()\fR and \fBsigtimedwait()\fR will
return the selected signal number. Otherwise, the function returns \fB\(mi1\fR
and sets \fBerrno\fR to indicate the error.
.SH ERRORS
.sp
.LP
The \fBsigwaitinfo()\fR and \fBsigtimedwait()\fR functions will fail if:
.sp
.ne 2
.na
\fB\fBEINTR\fR\fR
.ad
.RS 10n
The wait was interrupted by an unblocked, caught signal.
.RE

.sp
.ne 2
.na
\fB\fBENOSYS\fR\fR
.ad
.RS 10n
The \fBsigwaitinfo()\fR and \fBsigtimedwait()\fR functions are not supported.
.RE

.sp
.LP
The \fBsigtimedwait()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEAGAIN\fR\fR
.ad
.RS 10n
No signal specified by \fBset\fR was generated within the specified timeout
period.
.RE

.sp
.LP
The \fBsigwaitinfo()\fR and \fBsigtimedwait()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 10n
The \fIset\fR, \fIinfo\fR, or \fItimeout\fR argument points to an invalid
address.
.RE

.sp
.LP
The \fBsigtimedwait()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The \fItimeout\fR argument specified a \fBtv_nsec\fR value less than zero or
greater than or equal to 1000 million. The system only checks for this error if
no signal is pending in \fIset\fR and it is necessary to wait.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	Async-Safe
_
Standard	See \fBstandards\fR(7).
.TE

.SH SEE ALSO
.sp
.LP
.BR time (2),
.BR sigqueue (3C),
.BR siginfo.h (3HEAD),
.BR signal.h (3HEAD),
.BR time.h (3HEAD),
.BR attributes (7),
.BR standards (7)
